Recently, in the field of NAND-type flash memories, attention has been focused on a laminated-type (three-dimensional) NAND-type flash memory as a device that can achieve high integration without being restricted by the limit of resolution of the lithography technology. This type of three-dimensional NAND-type flash memory includes a laminated body and a semiconductor layer. In the laminated body, a plurality of conductive films and interlayer insulating films are alternately laminated. The conductive film functions as word lines and selection gate lines. The semiconductor layer is formed to pass through these laminated films. This semiconductor layer functions as a body of a memory string. Between the semiconductor layer and the conductive film, a memory film that includes an electric charge accumulating layer is formed.
This three-dimensional NAND-type flash memory has a large number of wirings and contacts for coupling various wirings and an external circuit together. Accordingly, it is required to reduce the resistance values of these portions.